It is well known to minimize the sensitivity of filter characteristics to values of the gain elements by minimizing the gain-sensitivity product (GSP) of the filter. For example, "Active Filter Design Handbook", by G. S. Moschytz and P. Hom, 1981, discloses using a computer program to design biquad active filters. The computer program presents flowchart listings to the designer and allows the designer to enter the specifications for the filter in terms of pole and zero frequencies and quality factors. In response to the data input by the designer, the computer program determines the minimum gain-sensitivity product (GSP). However, since the resistor values must be selected so as to minimize the GSP, this method results in only partial impedance tapering, namely, impedance tapering with respect to the capacitors of the circuit. Therefore, this method only minimizes the sensitivity of the filter characteristics to values of the gain elements.
Accordingly, a need exists for a method of designing filters which minimizes the sensitivity of the filter characteristics with respect to resistor and capacitor values while also minimizing the sensitivity of the filter to gain.